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(NoModeL) A. G. HOLOOMBE & G. A. OHEEVER.

Electrical Rook Drill.

No. 235,947. Patented Dec. 28, 1880.

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UNITED STATE PATENT OFFICE.

ALFRED G. HOLOOMBE, OF GRANBY, GONN., AND CHARLES A. GHEEVER, OF NEW YORK, N. Y., ASSIGNORS TO SAID CHARLES A. OHEEVER, TRUSTEE.

ELECTRICAL ROCK-DRILL.

SPECIFICATION forming part of Letters Patent No. 235,947, dated December 28, 1880.

Application filed July 30, 1880. (No model.)

To all whom it may concern:

Beitknown that we, ALFRED G. HoLooMBn, of Granby, in the county of Hartford and State of Connecticut, and CHARLES A. GHEEVER, of

the city, county, and State of New York, both citizens of the United States, jointly have invented certain new and useful Improvements in Electric Drills, of which the following is a specification.

Our invention relates to drillsof the class reciprocated by electro-magnetism. The application, No. 8,370, of Charles E. Ball, for electric rock-drills, filed April 26, 1880, shows such a reciprocating drill as having the ca- I 5 paci'ty of being driven positively in both directions by electro-magnetism. Our own application, No. 10,663, filed May 28, 1880, of which application this constitutes a division, likewise shows such a drill, together with mechanism for feeding it. We do not, therefore, broadly claim herein positively actuating the drill in both directions by electro-magnetism, nor, broadly, the feed mechanism, but limit our claims to the novel combinations and 2 5 organizations of old elements designated in the claims at the end of this specification, which relate, first, to an organization of mechanism whereby the drill, when fed forward, may rapidly be retracted to commence a new 0 forward movement; and, secondly, to certain improvements in the construction of the drilling part of the apparatus.

In the accompanying drawings, which represent our improvements as embodied in the 5 best way known to us at the date of filing this application, Figure 1 represents a longitudinal central section through so much of an elec tric drill embracing our improvements as is necessary toillustrate the subject-matterherein 4o claimed. Fig. 2 represents a plan thereof, and Fig. 3 a transverse section therethrough on the line 1 1 of Fig. 1.

The mechanism is shown as mounted in a skeleton -frame consisting of two heads or plates, jj, united by rods k. The lower or forward head or plate, j, is provided with sockets, in which are inserted longitudinallyadjustable legs 1, constituting a base or tripod upon which the mechanism is supported, and by means of which it may be adjusted at the proper angle relatively to its work.

Two properly-insulated coils or helices, c c, constituting ordinary electro magnets, are mounted in a sliding stock or frame, shown as consisting of head-pieces it, having the capacity of sliding upon the frame-rods Ic, and being united by rods i The apparatus in this instance is organized to actuate the drill positively in both directions by electro-magnetism, and is shown. as reciprocating verti- 6o cally. The coil 0 retracts the drill and its appurtenances, and actuates the feed mechanism, while the coil 0 imparts to the drilling-tool its forward working stroke. The latter coil is therefore preferably made larger or longer. Under the organization shown the effectiveness of the stroke is increased by the weight of the cores and their appurtenances supple- Inentin g the magnetic force.

The drilling-tool a is secured in suitable 7o well-known ways to a drill-stock, a, constituting an axial extension of the cores 1) (Z, which are similar to the soft-iron cores usually em; ployed in electro-magnets. They are shown as united by a bar or connecting-piece, f, of brass or other suitable non-magnetic material, so as to cause them to move together. The drill, cores, connecting-piece, and feed-bar all reciprocate in the same axial plane.

A polygonal guiderod or feed-bar, y, constitnting an axial prolongation of the core (1, works freely endwise through a corresponding aperture in the feed-wheel at, so as to compel both the feed-bar and feed-wheel to revolve together in order to actuate the feed mechanism, as hereinafter more fully described. The relative organization of the coils and cores is such that when the front core, I), is wholly within its coil 0, the rear or-lifting core, (Z, projects backward beyond the coil, as shown in 0 Fig. 1, and when the core d is wholly within its coil the core 1) projects beyond the forward end of the coil 0.

The automatic feed mechanism employed is similar to that described in our prior applica; 5 tion, with the exception hereinafter noted. The conical end h of the guide-rod, by its reciprocation, actuates a pawl on the feed-wheel on through a tappet or wiper, 0, and arm 0? on a rock-shaft, 0, provided with a retractingspring. The polygonal form of the guide-rod compels it and the tool-holder to rotate with the feed-wheel m, which latter wheel gears with a screw-wheel, a, likewise mounted on the same adjustable stock or arm as the feedwhee]. A screwed spindle, p, fixed rigidly in the head-pieces j j, passes freely through a central hole in this screwwheel n, on the upper surface of which two half-nuts, r, slide in suitable guides, being controlled by means of a ring, 8, provided with studs arranged to work in cam-slots in the nuts, (see Fig. 2,) so that as the screw-wheel rotates the half-nuts, being carried with it, gradually move forward on the screw 12, carrying the entire working mechanism with them. By reversing the movements of the ring the half-nuts release their grasp 011 the screw, and the working parts can be rapidly retracted. The half-nuts are locked on the screw by a pawl, f, catching in a notch in the rings. The parts are so proportioned that the normal feed imparted to the drill is equal to the distance it would pen etrate the softest substance upon which it is designed to operate. The conical head his so shaped and the stud or roller 0 on the arm 0 so adjusted relatively thereto that the pawl will move the wheel m the distance of one ratchet-tooth for eachfull stroke of the tool, and should the substance be hard enough to prevent the tool from making its full stroke the pawl will not catch over the succeeding tooth of the ratchet until the tool penetrates its full depth. The percentage of the stroke lost by the fa lure of the tool to catch on the ratchet-tooth is very small, so that it does not materially affect the momentum of the tool. By this organization the feed is perfectly regulated by the depth of penetration of the tool, and prevents the straining or breaking of the apparatus.

The coils c c are connected with a suitable generator of electricity in usual well-known ways by conductors t t, the current being alternately shunted through each coil, so as to move the drill positively in both directions. Our prior application, above mentioned, shows a rheotome or circuit-breaker for producing this alternation of currents disconnected from the drill, The application of Ball, above mentioned, shows a circuit-breaker actuated directly by the drill-stock.

Fig. 1 of the accompanying drawings shows amethod not only of actuating the circuitbreaker from the drill-stock, but also of regulating its action. This we do by means of adjustable tappets or wipers, consisting of screwnuts-w to, working on the screwed drill-stock. These screw-nuts act alternately on one arm of an elbow-lever or bell-crank lever, u, with which one of the conductors is connected, which bell-crank lever rocks on a pivot in a bracket or arm connected with the sliding stock or head 2'. The conducting-arm of this bell-crank lever vibrates between two insulated binding-posts, c 0, against either of which it is alternately held by a spring, a, and by a ring on a projection on the bell-crank lever, in a well-known way. Conductors v '12 a lead from the binding-posts to the terminals of their respective coils c c, to the other terminals of which the conductors t '0 are respectively connected.

The relation. of the parts shown in Fig. 1 is such that when the drilling-tool and cores are retracted to their greatest extent the forward or lower nut, to, presses the actuating-arm of the bell-crank lever backward and causes its conducting-arm to come in contact with the binding-post 17, thus allowing the current to flow through the wire o to the rear coil, 0', and through the conductor t back to the generator. This current causes the coil to act magnetically on the core (I, causing it to advance. thus driving the tool forward to its work, and at the same time pushing the core (I partly out of its coil 0. Just before the tool completes its forward stroke the rear nut, to, on the toolstock strikes the actuating-arm of the bellcrank lever and moves its actuating-arm from contact with the post 12 to contact with the post 1;, which latter is connected by the wire "0 to the forward coil, 0, through which the current passes by the wire Q74 to the returnwire 15. The current is thus shunted through the coil 0 to the coil 0, and its action retracts the core 2) within the coil 0, correspondingly retracting the tool, and at the same time movin g the rheotome or circuitbreaker back to the position shown in Fig. 1, when the operation above described is repeated. The tool is thus positively reciprocated in both directions at measured intervals so long as the coils are in circuit. The rapidity of the stroke can be regulated by moving the screw-nuts backward or forward on the drill-stock, it being obvious that as they are brought nearer together the rapidity of the stroke will be qnickened, while the contrary movement would diminish such rapidity.

The actuating-arm of the bell-crank lever is made somewhat flexible, to enable it to yield slightly after the conducting-arm has come in contact with the pieces 10 by the pressure of the nut to on it when the tool is working at its full stroke, the effect of which is to give the maximum degree of feed, as the stud 0 is thereby caused to descend on the conical point h, and thus give a longer stroke to the feedpawl o, hereinbefore described. A bufferspring of suitable material interposed between the nut to and the slidingstock counteracts the jar which would otherwise occur were the rapid backward motion given to the tool by the magtogether and the momentum utilized on the working stroke.

2. The combination, substantially as herein set forth, of the coils or helices, the cores reciprocating therethroug'h, the drilling-tool connected with the cores, and theinterposed buffer-spring, which diminishes the shock of the tool on its backward motion, and the resilience of Which springincreases the nioinentui of the working stroke.

3. The combination, substantially as herein set forth, of the coils, the cores, the drillingtool carried thereby, adjustable tappets or wipers on the drill-stock, the circuit-breaker, and the connecting-wires, whereby the rapidity of the stroke may be regulated.

4. The combination, substantially as herein set forth, of the main frame, the stock or tool holder adjustable therein, the coils, the cores, the drilling-tool and feed-bar mounted thereon, a feed-screw fixed on the frame, half-nuts embracing said screw, and mechanism, st stantially such as described, for rotating t half-nuts by the reciprocation of the feed-bar, automatically to regulate the feed of the tool.

5. The combination, substantially as herein set forth, of the frame, the stock adjustable therein, the coils carried by the stock, the cores reciprocating in the coils, the drillingtool carried by the core, the feed-bar, also carried by the core, automatic feed mechanism, substantially such as described, and a rheotome actuated by the drill-stock to render the feed and the working of the drill both automatic.

In witness whereof we have hereunto set our hands this 28th day of July, 1880.

ALFRED G. HOLCOMBE. CHAS. A. GHEEVER. Witnesses:

WILLARD L. OANDEE, ALFRED SHnDLocK. 

